Vanadium salts of acid esters as inhibitors in lubricating oils



Patented Nov. 6, 1945 UNITED STATES PATENT OFFICE VANADIUM SALTS OF ACID ESTERS AS INHIBITORS IN LUBRICATING OILS Frederick C. Frank, Pitman, and Darwin E. Badertscher and Henry G. Berger, Woodbury, N. J., assignors to Socony-Vacuum Oil Company, Incorporated, New York, N. Y., a corporation of New York No Drawing. Application March 17, 1942, Serial No. 435,082

2 Claims.

bustion engines, will, as the result of oxidation underlnormalconditions of use, develop substantial quantities of carbonaceous deposits which accumulate as sludge or carbon deposits impairing the free flow of the oil, and which deposit about the piston rings, causing them to stick and filling the slots in the oil rings. There is also developed, as the result of oxidation, substantial acidity in the 'oil which has a deleterious efiect upon contacted metals, particularly certain types of alloy bearing metals; and in the event the oil is being used as a dielectric, the development of acidity obviously reduces its efficiency in this respect.

Numerous additive agents or oxidation inhibitors have been developed for use in mineral oils to retard or counteract the eiiects of oxidation. In general. the more efiective of these oxidation inhibitors when incorporated in mineral oil fractions will inhibit the effects of oxidation upon the oil for a limited time; and when the oil composition is removed from the engine in which it has been used and is substituted by a mineral oil fraction which does not contain an oxidation inhibitor, the oil will deteriorate during use. Thus, there is no carrying over of the efiect of the inhibited mineral oil to a blank mineral oil used in a succeeding engine operation.

The present invention is predicated upon our discovery of a. novel class of oxidation inhibitors and is broadly directed to viscous mineral oil compositions which have been inhibited against oxidation by the incorporation therein of one or more compounds or compositions belonging to this general class. The improving agents contemplated herein as oxidation inhibitors belong to the general class of metal salts or soaps of organic acids. More specifically, the present invention is predicated upon the discovery that the vanadium salts of certain types of organic acids possess unique properties as, lubricating oil addition agents. Broadly stated the compounds contemplated herein are the vanadium salts of acid esters of polycarboxylic acids in which the hydrogen of one carboxyl group has been replaced with an alicyclic or aliphatic hydrocarbon group containing a sufln cient number of carbon atoms or an aliphatic group of sufliciently high molecular weigjht to solubilize the compound in viscous mineral oil; and particularly preferred for the purposes of the present invention are the corresponding vanadyl salts.

Compounds'of thisgeneral class of vanadium salts or soaps, particularly the vanadylsalts or soaps, are not only extremely efiective as oxidation inhibitors when used in internal combustiond enginea'but'they' also'po'sss's tfi s urprising property of conditioning the engine parts in some Way, so that when the inhibited 'oil is removed from the engine in which it has been used and an uninhibited oil subsequently used in the engine, the uninhibited oil will not undergo the deterioration which would normally be encountered in such use. This remarkable property is not fleeting nor limited to one following engine run, but continues in efiect for a number of such subsequent engine operations. In efiect, we have discovered that by lubricating an engine-as, an internal com-bustion enginewith a mineral oil containing one or more of our novel vanadium-organic compounds, as vanadyl-organic compounds, uninhibited mineral oils subsequently used in the engine will be, in fact, inhibited by some as yet unexplained action of the additive.

The aforesaid conditioning action appears to" be critical with vanadium salts-as typified by the vanadyl salts f the acid esters described above, for the corresponding salts of other polyparting this surprising conditioning effect to the engine. 7

The acid esters, from which the salts contemplated herein are obtained, can be formed by the reaction of. aliphatic or al-icyclic alcohols with an aliphatic, cycloaliphatic or aromatic polycarboxylic acid. Typical polycarboxylic acids which may be used are maleic, succinic, malonic, phthalic, etc. The vanadium salts may be formed by first neutralizing the acid with an alkali alcoholate or alkalimetal hydroxide to form. the alkali metal salt and then effecting a so-called metathesis with an inorganic vanadium salt.

In the case of acid ester salts derived from the dicarboxylic acids, which have been used to demonstrate the eifectiveness of the compounds contemplated herein, these compounds may be represented by the general formula:

in which R represents the mineral oil-solubilizing aliphatic or alicyclic group which we have discovered should contain at least three carbon atoms to give the desired property of oil-miscibility in the product; a: represents a whole number which may be 2, 3, 4 or 5; and the group may be described as representing the residue of an aliphatic, alicyclic, or aromatic dicarboxylic acid. In certain of the compounds synthesized inclusive of the true vanadium salts, vanadylsalts and the like.

Particularly preferred, however, for the purposes of the present invention arethe vanadyl salts of the acid esters hereinbefore described, which are represented by the following general formula:

in which R and R are as given above.

From the foregoing it will be seen that the compounds contemplated herein as oil-improving agents may be broadly classified as the vanadium salts of an acid ester of a polycarboxylic acid wherein the hydrogen of at least one carboxyl group is replaced with an aliphatic or alicyclic group having at least 3 carbon atoms.

The synthesis of salts of the type contemplated by this invention is illustrated by the following description of the procedure followed in preparing vanadyl oleyl-phthalate.

EXAMPLE I Vanadyl oleyl phthalate was prepared in three separate stages: 1

(a) HYDROGEN OLEYL PHTHALATE A mixture of 268 grams (1 mole) of commercial oleyl acohol, 268 grams (1.8 moles) of phthalic anhydride and 1000 c. c. of benzene was distilled until 400 c. c. of benzene had been removed (to make the mixture anhydrous). The distillation residue Was then stirred and refluxed on a hot water bath for 7.25 hours. After cooling over night the mixture was filtered ofi by suction. The unreacted phthalic anhydride from this filtration weighed 95 grams. The filtrate was vacuum distilled on the water bath to remove the benzene. The cold distillation residue which had deposited more phthalic anhydride, was filtered and the phthalic anhydride Washed in the filter with petroleum ether. The phthalic anhydride thus recovered weighed 27 grams. The petroleum ether was evaporated and the residue combined with the main bulk of the product. The total recovery of unreacted phthalic anhydride was 122 grams (theoretical recovery, 120 grams). The total yield of product with a neutralization number of 138.0 (theoretical, 139.3) was 395 grams, 95 of that required by theory.

(1)) SODIUM OLEYL PHTHALATE To a solution of sodium ethylate prepared from 5.5 grams of metallic sodium and 75 cc. absolute alcohol was added with stirring a solution of 100 grams hydrogen oleyl phthalate in 200 cc. petroleum ether. Removal of the alcohol and petroleum ether by vacuum distillation on the water bath yielded as a residue 100 grams of a solid, somewhat hygroscopic soap.

(0) VANADYL OLEYL PHTHALATE To a solution of sodium oleyl phthalate prepared by the action of 7 grams of sodium and 25 cc. absolute alcohol on a solution of 127 grams of hydrogen oleyl phthalate in 250 cc. dry benzene, was added 28 grams of syrupy vanadyl chloride which is a hydrate, possibly (Cf. Merck's Index). The mixture was refluxed with stirring in an apparatus with a water takeoff" so that the water in the vanadyl chloride was removed and the mixture made anhydrous. Th mixture was then filtered free from sodium chloride-and thebenzene evaporated 'leaving 'l38 grams of a dark green, viscous liquid (theoretical yield 137.5 grams).

The vanadium salts, as typified by the vanadyl salts, contemplated by this invention are highly viscous products and are soluble in mineral oil when the aliphatic ester constituent is comprised of three or more carbon atoms. Other typical vanadyl salts contemplated by the present invention are vanadyl oleyl succinate, vanadyl oleyl malonate, vanadyl oleyl maleate, vanadyl oleyl tetrahydro phthalate, etc.

To demonstrate the efiectiveness of the vanadium-organic salts contemplated by this invention as oxidation inhibitors for viscous mineral oils, we .have subjected samples of an unblended oil and a blend of the same oil containing the improving agent to the Bubble test, which com prises the following. A section of bearing con taining a cadmium-silver alloy surface and weighing about 6.0 grams was placed in 30 grams of a commercial S. A. E. 20 solvent-refined motor oil. .The oil was heated to about C. for 22 hours while a stream of air was bubbled against the surface of the bearing. The weight loss in milligrams of the bearing is interpreted-as a measure of the corrosiveness of the oil. The inhibited and uninhibited oil samples were run concurrently, the results of which' are given in Table I below.

To further demonstrate the effectiveness of the salts contemplated by this invention as oxidation inhibitors for viscous mineral oils, we have subiected lsamnles of an unblended solvent-refined S. A. 30 motor .oil and a blend of the same oil containing our typical improving agent to an Oxidation susceptibility test. In this test,

vention as oxidationinhibltors :for viscous mineral oils is given by the results of the Accelerated ring sticking test. The engine employed in this test was the standard C. F. .R. 'fKnock test en- .300 gram samples of oil in pyrex glass beakers 5 gine which is cooled with a .dieth'ylene glycol-wawere maintained at 350 F. and 2 liters of air per ter mixture held at about 400 F. The engine hour were blown .over the surface while the samwas run at a speed of approximately 12.90 R.--P.. M. 9165 were stirred constantly with steel paddles. with the throttle :set just below detonation, "11s- Samples were withdrawn at specified intervals ing a compression ratio of 7:1. The .runs'were and the-volume-percent'age of sludge determined. 10 normally for 28 hours, with an inspection'of the The results of this test .are given below in Tapiston at 14 hours. At the end of the test the ble II. piston was examined .for stuck rings, ring slots Table II filled with carbonaceous deposits and total deposits. The acidity 'or neutralization number Sludge'vomme (NN.) of the used oil and the kinematic vispercentage cosity of the used oil were determined. The oil Matenala-dded percent used was a lubricating oil stock of 120 seconds ;3.days5days 7days Saybolt Universal viscosity at 210 F. and the results of the consecutive engine runs are tabu- None 12 lated in Table III. After each engine run with 9M1 Phflmlate 9' L0 an oi1 blend, at least one run was made with the fresh unblended oil-to determine the carry over" The'most impressive demonstration of the efeffect of the additive which was in the oil blend fectiveness of the salts contemplated by this inin question.

TableIII Rin sme'greessmck fi a 115011511 Percent Nm Additive hymn Hours I deposits 0 v:

. 2g 33g 36g 3.6g. 13 9g 2 10.6 -30.-14 -20 11 1mm .1 t 65,, 1.0 1 ,4f j umgley'phhala "180 u .0; '0. 0-

. '01 -0 528 41. 12 2.5 m -fNmn-- 14; .360 360 o .o 25 ---10 T: 9.45 26.81 1.2

' I 28 R1131 'stopged ati hougs, ring; tug Tr Tr Bari 1 1' thalat 1.0 14 i 1 r i W e 28 .360 o 0 i0 0 5. 5 Ti 1.05 30.60. .a.-0 3b Nnnn 14 360 0 360 '0 0 1 2 "3% 368., 66g .368 663 9 83 5 1&15 50.4 11.2 4a .Qobaltous. oley phthaiate 1.. 28 m o 0 33-1 26 4b Nnnn 14' 150 0 .-0 0. '0. 50. -15. TI 1 26; 860 0. 360. .360 v560. 90 65. .20. 1293 29.60 22 5g .Ferrousoleyl phthalate 1.0 14 360 360 360 360 120 20' 20 10 10.1 26.58 1.7

28 Run stopped at 14 hours a, 555 14 360 0 360 T. 0 40 a0. 5

' 28 360 360 360 360 360 10- a5 25 14.1 29.16 2.3 60 -Mang'anous ole'yl'phthalate 1.0 14 360 0 0 0 .0 0 0 0 28 .360 130 3.60 120 360 5 .5 5. 0.0 68.06 0.1 am 14' 360 0' 1210 T 0 40 10 28 360 360 360 360 360 85 15 10.0 29.04 1.5 Stannousoleylphthalate...v 1.0 14 30 0 0 0 0 5 Tr. Tr.

28 360 0 0 -0 0 15 5 Tr 6.0 29.40 2.2 14 0 0 360 VT VT 15 20 10.

I as 220 0 360 360 360 05 .90 85 16.8 22.55 1.1 Vanadyloleylphthalate 1.0 14 0 0- 0 0 0 0 2s 0 0 0 0 0 0 0 0 3.5 24. 98 0.6 None 14 0 0 0 0 0 0 0 0 2s 0 0 0 0 0 0 0 0 6.4 26.18 0.5 84: do 14 0 0 360 0 0 15 10 Tr 2s 0 o 360 360 210 B0 10 Tr 10.0 26. a0 1.0 Rd 115 14 0 T o 0 0 0 5 Tr 2s 0 30 360 360 360 0 40 20 16.9 21.66 2.5 a, do 14 0 0 0 0 0 15 15 Tr 2s 0 0 360 360 0 s5 15 5 12.35 28.05 1.6 8] (In 14 360 0 360 T 0 40 30 5 28 360 360 360 360 360 15 85 25 141 29.76 as Rn (in 14 360 360 0 0 25 5 T 2a 360 360 360 210 T 15 15 20 12.25 28.93 1.4 90 Vanadyloleyl phthalate 0.25 14 0 0 0 0 0 0 0 0 2s 0 0 0 0 0 o 0 0 5.65 26.05 0.5 Nnna 14 0 0 0 0 0 Tr Tr Tr 2s 0 0 360 330 0 20 10 0 8.60 21.29 1.2 96 "do 14 0 0 '1 T T 20 10 Tr 2s 0 360 360 180 50 50 10 12.25 28.28 1.1 0,1 (In 14 o 0 360 T T 15 15 5 Tr-trace. T-tacky. VT-very tacky.

by the same number and the subscription b, or 0, etc., were made with fresh uninhibited oil without cleaning the engine after the blend of oil and additive had been removed. Prior to each initial a run with the oil blend containing the designated additive, the engine was thoroughly cleaned. These data were obtained to demonstrate the aforesaid carry-over effect of the vanadium compounds, as illustratedby vanadyl compound, an eifect not present in the corresponding compounds of the other metals tested. The vanadium compounds, particularly the vanadyl compounds, appear to be uniqueinthis 4 4b.' b; 6a6b, and 7a--7b indicate that" the additives in which the metal'is other than vanadium-'-are efiective for onlythe engine 'run in which the'oil blend is used, and indicate also that the unblended oilis not improved by the use of the blended oil in a preceding engine run.

The results of engine runs 80. and 8b on the other hand demonstrate not only the effectiveness of the, vanadium sa-ltas typified by a' vanadyl saltin the oil (as shown by 8a), but also the carry-over efiectof the vanadium salt to the unblendedoil in the succeeding engine run (as shown by 8b) Here it will be observed that the piston ring condition was the same with the refill oil at the end of 28 hours as it was with the 'blend (run 811) whereas the blank oil in a cleanengine (run-No= 1) showedsubstantial ring sticking at the end of 28 hours. Further, the

with any of the foregoing in which 1.0% of salts of other metals were used, it is readily seen that the smaller amount of the vanadium salt is much more effective than the larger amount of the salts of other metals, as, for example, Al, Ba, Co, Fe, Mn and Sn.

Thus, from the foregoing results, it will be seen that the vanadiumand particularly the vana-' dylester acid salts of the type contemplated by this invention, when blended with a viscous mineral oil, retard to a substantial degree the deleterious eflects of oxidation. The results of the Accelerated ring sticking test are particularly striking for they indicate that the vanadium salts as described herein are unique in imparting the above-described conditioning effect to engine parts, an effect not characteristic of corresponding salts of other poly-valent metals.

Improving agents of the type described above may be blended with mineral oil fractions in various proportions depending upon the oil fraction and the conditions under which it is used. In general, a satisfactory product may be' obtained with about of the improving agents,

but amounts ranging from 3% to 2% may be used.

Our invention is not limited to the specific examples given herein but includes within its results of engine run 8b when compared with the results of the refill engine runs2 3b, 4b, 5b, 6b and 7b-in which metal salts other than the vanadium salt had been used in prior engine runs,

scope whatever changes or modifications fairly come within the spirit of the appended claims.

We claim:

1. A mineral oil composition comprising a. viscous mineral oil fraction and in admixture therewitha' minor -proportion sufficient-to; inhibit ox-' idation, of vanadyl oleyl phthalate, said'phthalate" having the property of, inhibiting ring-sticking of pistons even after it is removed and the-pistons are contacted with a compounded or non-oompounded mineral oil.

' 2. A mineral oil composition comprising a. viscous mineral oil fraction and in admixture therewith a minor proportion, from about 1 5% to about 2%, of vanadyl oleyl phthalate, said phthalate having the property of inhibiting ringsticking of pistons even after it is removed and the pistons are contacted with a compounded or non-compounded mineral oil.

FREDERICK C. FRANK. DARWIN E. BADERII'SCHER. HENRY G. BERGER. 

